Electric arc discharge tube



Feb. 11, 1936.

G. ZECHER ELECTRIC ARC DISCHARGE TUBE Filed Oct. 28, 1930 I a 6 Z 2 h T I a m 7 e 5 Jase 772 62/572 56% 4 Patented Feb. 11, 1936 UNITED STATES ELECTRIC ARC DISCHARGE TUBE Gustav Zecher, Eindhoven, Netherlands, assignor, by mesne assignments, to General Electric Company, a corporation of New York Application October 28, 1930, Serial No. 491,769 In the Netherlands January 9, 1930 6 Claims.

layer of disintegrating particles of materialformed on the wall renders difiicult the issue of the rays to be emitted and causes a considerable decrease in efi'iciency of the discharge tubes.

The invention has for its object to obviate these difficulties.

For this purpose, an electric arc discharge tube according to the invention for the emission of rays being filled with gas or vapour or a mixture thereof and comprising an incandescent cathode and one or more anodes contains a grid-shaped member which, without surrounding the path of discharge, is arranged laterally of this path and which is preferably electrically connected to the incandescent cathode. It has been found that this grid-shaped member prevents the wall from being blackened by intercepting and attracting a very great part of the disintegrating material. Thus, not only the part of the wall which, viewed from the path of discharge, is situated behind the grid-shaped member remains free from precipitate but practically no precipitate is found to be formed on the part of the tube wall that is not directly screened by the member. It is to be understood that the grid-shaped member arranged laterally of the path of discharge can not be in alignment with the said path.

40 In order that the invention may be clearly understood and readily carried into effect one form of discharge tubes according to the invention will be described with reference to the accompanying drawing.

' 45 The electric discharge tube shown in thefigure coated with intensely emitting substances, for example thorium or oxides of alkaline earth metals. Lateral to the path of the discharge formed between the cathode and the anodes is a grid-shaped member which consists of a frame 5 on which .a 5 wire 6 is wound intothe form of a grid. The frame 5 is secured by means of a supporting wire i to the supporting wire 8 of an incandescent cathode, which wire similarly to a supporting wire 9 serves to supply the incandescent cathode with 0 current. The supporting wires of the anodes by means of which the latter are fixed to the pinch and through which the electric current can be suppliedare designated by ID and I I.

The tube shown on the drawing contains a sup- 15 ply of mercury vapour and for this purpose one or more drops of liquid mercury may have been inserted into the discharge tube. In addition to the mercury vapour the tube contains a supply of gas which may, preferably, be a rare gas, for example argon. The pressure of this gaseous filling may have Various values and is preferably low, for example of the order of several millimeters, or less of mercury pressure.

During the operation of the discharge tube illustrated an arc discharge is struck between the incandescent cathode and the anodes which causes particles of material to disintegrate from the cathode, said particles being retained by the grid-shaped member arranged laterally of the path of discharge, since the grid-shaped member 5, 6, due to its electrical connection with cathode 3, is negatively charged to attract the positively charged particles of disintegrated cathode material. Thus, not only the part of the tube wall Which, viewed from the incandescent cathode, is situated behind the grid-shaped member but also the remaining part of the tube wall remains free from precipitate so that the transparency of the wall to the ultra-violet rays generated in the tube is practically not decreased during the operation of the tube.

Obviously, it is not necessary that the shape of the grid-shaped member should always be that of the member shown in the figure, but any other suitable shape, for example the shape of gauze, may be used.

What I claim is:

1. An electric discharge lamp device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being an elongated cathode of disintegratable material, two of said electrodes being plate shaped anodes mounted in parallel positions in said container, said cathode being interposed between said anodes and a grid in said container mounted at right angles to the longitudinal axis of said cathode parallel to the discharge path between said electrodes and interposed between said cathode and a light transmitting part of said container.

2. An electric discharge lamp device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being a thermionic cathodeof helical shape and of disintegratable material, two of said electrodes being plate shaped anodes, said anodes being mounted on opposite sides of said cathode and parallel to the axis of said cathode, a grid in said container mounted substantially at right angles to the axis of said cathode and interposed between the cathode and a light transmitting part of said container and along one side only of the discharge path to intercept the particles of light absorbing, disintegrated cathode material.

3. An electric discharge lamp device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being a thermionic cathode of helical shape and of disintegratable material, two of said electrodes being plate shaped anodes, said anodes being mounted on opposite sides of said cathode and parallel to the axis of said cathode, a negatively charged grid in said container mounted substantially at right angles to the axis of said cathode interposed between the cathode and a light transmitting part of said container and along one side only of the discharge path to intercept and attract the patricles of light absorbing, disintegrated cathode material.

4. An electric discharge lamp device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being a thermionic cathode of helical shape and of disintegratable material, two of said electrodes being plate shaped anodes, said anodes being mounted on opposite sides of said cathode and. parallel to the axis of said cathode, a grid in said container electrically connected to said cathode and mounted substantially at right angles to the axis of said cathode interposed between the cathode and a light transmitting part of said container and along one side only of the discharge path to intercept and attract the particles of light absorbing, disintegrated cathode material.

5. An electric discharge lamp device comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being a thermionic cathode of helical shape and of disintegratable material, two of said electrodes being plate shaped anodes, said anodes being coextensive with and mounted on opposite sides of said cathode and parallel to the axis of said cathode, a grid in said container mounted substantially at right angles to the axis of said cathode, interposed between the cathode and a light transmitting part of said container and along one side only of the discharge path to intercept the particles of light absorbing, disintegrated cathode material.

6. An ultra-violet generator comprising a container, a gaseous atmosphere therein, electrodes sealed therein, one of said electrodes being an elongated cathode of disintegratable material, two of said electrodes being plate shaped anodes mounted in parallel positions in said container, said cathode being interposed between said anodes .and a grid in said container mounted at right angles to the longitudinal axis of said cathode, parallel to the discharge path between said electrodes and interposed between said cathode and a light transmitting part of said container.

GUSTAV ZECHER. 

